Have your 6 year old son avoid drinking anything an hour before bed and have him go to the toilet 3 times at least before during that hour before bed to help him empty out his bladders as much as possible.
If he goes to bed with an empty bladder he will be less likely to wet the bed. Although he will still be filling up his bladder during sleep.
It just gives his bladder more room for the new urine.
Also set an alarm to wake you up about 2 hours after he goes to bed and wake him up and take him to the bathroom and have him empty his bladder again.
There's also bed wetting alarms that you can get that you place a sensor on the kids underwear and when it detects wetness it should wake the child up if he's not a sound sleeper.
Since he doesn't want to wear goodnites you can get Disposable Bed Mats that goodnites also sells.
You place them on the bed and they absorb the urine that the bed would've absorbed.